The invention relates to a wheel suspension of a motor vehicle, with a wheel carrier which is connected to the vehicle body via wheel-guiding and wheel-steering components and which, by rolling-bearing mounting, carries at least one wheel via a wheel hub.
In the event of operations for the acceleration and braking of a motor vehicle, longitudinal forces act on the individual wheels. Moreover, during driving on a, for example, uneven road, shocks occur on the wheels. These are generally absorbed in elastomeric elements which are usually arranged where the wheel suspension is fastened to the vehicle body. The damping of these elastomeric elements determines the longitudinal spring comfort of the vehicle. In this case, the entire vehicle axis is often shifted in the longitudinal direction of the vehicle. At the same time, during acceleration and braking, the level of the vehicle body is changed, the toe-in of the vehicle being influenced. In this case, the angle of the wheels to the direction of travel may change and the tire wear may increase.
German Published Patent Application No. 198 32 384 describes an individual wheel suspension, in which a sliding pivot joint with a swing arm having two approximately vertically oriented pivot axes is arranged between the wheel carrier and a semi-trailing arm. During braking, the individual wheel is pivoted about the pivot axes and brings about a change in the toe-in in a specific manner.
It is an object of the present invention to provide a wheel suspension which increases the driving comfort of a vehicle in the event of shocks on the wheels during acceleration and deceleration operations and reduces the tire wear.
The above and other beneficial objects of the present invention are achieved by providing a wheel suspension as described herein.
According to the present invention, the wheel carrier includes a vehicle-body-side and a wheel-side wheel-carrier part. The vehicle-body-side and the wheel-side wheel-carrier part are connected movably relative to one another via a sliding or a pivot joint, the wheel-carrier parts having a preferential position in relation to one another. The direction of the relative movement between the vehicle-body-side and the wheel-side wheel-carrier part extends approximately in the direction of travel or in the direction opposite to the direction of travel. Moreover, between the wheel-carrier parts elements are arranged which reverse the joint movement and which return the wheel-carrier parts in the direction of the preferential position.
Sliding or pivot joints are arranged between the vehicle-body-side and the wheel-side wheel carrier. Shock forces and longitudinal forces acting from outside and caused, for example, by longitudinal accelerations or longitudinal decelerations of the vehicle induce a relative movement of the parts of the wheel carrier in relation to one another. In this case, these parts move out of a preferential position and, when the positive or negative acceleration decreases, are returned into a preferential position relative to one another again by returning elements, for example spring/damper elements. The relative movement takes place approximately in the direction of travel. The toe-in of the individual wheel may be thereby maintained during the deflection of the sliding or pivot joint. The wear of the tires is not increased.
Longitudinal forces due to accelerations and shock forces are absorbed in the sliding or pivot joints between the vehicle-body-side and the wheel-side parts of the wheel carrier. The longitudinal spring comfort and driving comfort are thereby increased. During the absorption of the forces, only the wheel, together with part of its wheel suspension, may be moved, and the axle maintains its position on the vehicle body. There is no need for elastomeric elements for absorbing these longitudinal forces between the wheel suspension and the vehicle body.
This wheel suspension may be used in the case of both driven and non-driven wheels on front and rear axles and also with various axle configurations, such as, for example, a composite link axle, a semi-trailing arm axle, etc.
The direction of the relative movement may take place both in the direction of travel and in the direction opposite to the direction of travel, depending on the load on the individual wheel.
Acceleration forces are applied in the wheel contact area of the motor vehicle. They act on the sliding and/or pivot joints as a moment with the lever arm corresponding to the distance between the wheel contact area and the guide element nearest to the wheel contact area.
Shock forces, which act on the wheel, for example, when the vehicle drives over a deep pothole, take effect as a momentum on the wheel. They are applied at least approximately parallel to the road along the wheel-center transverse plane.
A sliding joint may comprise, for example, two linear guides parallel to one another. The play of the sliding joint is then smaller, due to the double guide, than in the case of a single guide.
A pivot joint may include a ball joint. When the wheel is loaded by a shock force or acceleration force, this joint remains at a fixed location with respect to both parts of the wheel carrier.
If one of the guides or a joint is below the wheel rotation axis, this, in particular, may be subjected to load during acceleration operations. If, for example, it has a higher rigidity than a second guide arranged at a higher level, as a result of acceleration forces, the load leads to a pivoting movement about the lower guide or the lower joint. The position of the wheel contact area may be approximately maintained in relation to the joint. The flexibility of the sliding or pivot joint under this load is insignificant.
In this case, when shock forces take effect, both the upper guide and the lower guide are subjected to load. The rigid lower guide is compressed to a lesser extent than the softer upper guide. The wheel rotation axis creeps rearwards in relation to the wheel contact area. The flexibility of the sliding or pivot joint under this load is high.